What Happened in CLEF 2005 -- I. Multilingual Textual Document Retrival (Ad Hoc) -- Cross-Language and More -- Monolingual Experiments -- II. Domain-Specific Information Retrieval (Domain-Specific) -- III. Interactive Cross-Language Information Retrieval (iCLEF) -- IV. Multiple Language Question Answering (QA@CLEF) -- V. Cross-Language Retrieval In Image Collections (ImageCLEF) -- VI. Cross-Language Speech Retrieval (CL-SR) -- VII. Multilingual Web Track (WebCLEF) -- VIII. Cross-Language Geographical Retrieval (GeoCLEF) -- Evaluation Issues.

The sixth campaign of the Cross Language Evaluation Forum (CLEF) for European languages was held from January to September 2005. CLEF is by now an established international evaluation initiative and 74 groups from all over the world submitted results for one or more of the different evaluation tracks in 2005, compared with 54 groups in 2004. There were eight distinct evaluation tracks, designed to test the performance of a wide range of systems for multilingual information access. Full details regarding the design of the tracks, the methodologies used for evaluation, and the results obtained by the participants can be found in the different sections of these proceedings. As always the results of the campaign were reported and discussed at the annual workshop held in Vienna, Austria, September 21-23, immediately following the ninth European Conference on Digital Libraries. The workshop was attended by approximately 110 academic and industrial researchers and system developers. In addition to presentations by participants in the campaign, Noriko Kando from the National Institute of Informatics, Tokyo, gave an invited talk on the activities of the NTCIR evaluation initiative for Asian languages. Breakout sessions gave participants a chance to discuss ideas and results in detail. The final session was dedicated to proposals for activities for CLEF 2006. The presentations given at the workshop can be found on the CLEF Web site at: www. clef-campaign. org. We should like to thank the other members of the CLEF Steering Committee for their assistance in the coordination of this event.